Standardization in the turbo outlet duct end of the engine (second duct hereinafter) on the part of each manufacturer makes it necessary to design a quick connecting device particularly and accurately adapted to manufacturing requirements. As a general rule, the second duct, particularly sized according to each manufacturer, is provided with a coupling end (referred herein to as male member) wherein said air cooling duct is to be coupled (first duct hereinafter) through a quick connecting device. Said coupling end of the above mentioned second duct is adapted for snugly receiving a fastening clip which purpose is to hold in place the first and the second ducts through said quick connecting device.
Quick connecting devices currently being manufactured for this purpose are formed basically of a female bush-like tubular body associated with said first duct, that is, with the air cooling duct coming out from the turbo of the motor vehicle engine. The inner surface of said female bush is suitably adapted to fit the outer surface of said second duct end (that is to say, the male member). Said male member has a peripheral groove where a sealing o-ring is received.
When assembled, the first duct end (female member) is attached to said tubular body (male member) that is fitted therein so that the female member covers said circumferential groove of the male member.
The female member, that is, the first duct end, has typically a groove complementary to the groove of the male member to allow coupling of the fastening clip.
Although the design of these coupling devices is advantageous in the sense that an easy and comfortable coupling in assembly, maintenance and repair operations of the ducts being connected is achieved, however it has been found in practice that the working conditions that the connecting device is subjected (high temperatures and vibrations) result in many connecting faults. In particular, it has been found that the female member is usually broken since, as stated before, vibrations to which it is subjected in conjunction with the high temperatures to which it is also subjected result in expansion of the circumferential groove thus forming a crack leading to fatigue cracking of the coupling end of the cooling duct (first duct). This problem has forced users using said connecting system to take their motor vehicles for repairing so that said quick connecting device is duly replaced for a new one.
Later attempts have been carried out for overcoming these problems. One of the proposed solutions at present for reducing the possibilities of breakage of the connecting device consists, for example, in increasing the wall thickness in the connecting area, specially in the connecting area where the circumferential groove of the female member is formed, that is the area where the breakage of the device begins. However, machining difficulties for obtaining the final piece with this increased thickness at a given area and the increase of material required result in a considerably increased cost of said device.